1. Field of the Invention
The present invention relates to an improved portable display device, and more particularly to a portable display device with an enhanced stiffness.
2. Discussion of Related Art
Recently, various flat display devices have been developed having reduced weight and size. Exemplary flat display devices include a liquid crystal display, a field emission display, a plasma display panel, an organic light emitting display, etc. Specifically, liquid crystal displays have become popular due to their small size, light weight, and low power consumption. Liquid crystal displays may be mounted in large-sized television monitors as well as mobile phones and personal digital assistant (PDA).
FIG. 1 is an exploded prospective view illustrating a conventional portable display device. FIG. 2 is an assembled sectional view taken along line A-A′ of the portable display device shown in FIG. 1.
Referring to FIGS. 1 and 2, the conventional portable display device includes a liquid crystal display panel 4, a backlight assembly 50, a bottom chassis 22, a first printed circuit board 24, a second printed circuit board 26, and a light-emitting display panel 30.
The liquid crystal display panel 4 displays predetermined images and includes a first substrate 4a, a second substrate 4b and a liquid crystal (not shown) injected between the first substrate 4a and the second substrate 4b. 
The second substrate 4b includes a plurality of thin film transistors (TFTs) arranged in matrix form. A source electrode of the TFT is connected to a data line, and a gate electrode thereof is connected to a scan line. A drain electrode of the TFT is connected to a pixel electrode made of transparent indium tin oxide (ITO) of a conductive material. The TFT is turned on when the scan line is supplied with a scan signal, and supplies a data signal from the data line to the pixel electrode.
An integrated circuit 6 is inserted on one side of the second substrate 4b, and the data signal and scan signal are supplied from the integrated circuit 6. A protective layer 8 is deposited around the integrated circuit 6.
The first substrate 4a is arranged facing the second substrate 4b. A common electrode made of ITO is applied on a front surface of the first substrate 4a. The common electrode is applied with a predetermined voltage, to generate an electric field between the common electrode and the pixel electrode. The array angle of the liquid crystal injected between the first substrate 4a and the second substrate 4b varies with the electric field, and the optical transparency varies according to the array angle to thereby display desired images.
The backlight assembly 50 includes a mold frame 16, light emitting diodes (LEDs) 12, a LED substrate 14, a light guide plate 18, a reflective plate 20 and optical sheets 10.
The LEDs 12 emit a predetermined amount of light corresponding to a drive signal from the LED substrate 14. The light guide plate 18 supplies the light from the LEDs 12 to the liquid crystal display panel 4.
The reflective plate 20 arranged on the back surface of the light guide plate 18 reflects incidence light from the light guide plate 18 back onto the light guide plate, thereby improving optical efficiency.
The optical sheets 10 enhance the amount of light from the light guide plate 18 to the liquid crystal display panel 4.
The LED substrate 14 connected to the first printed circuit board 24 supplies the drive signal to the LEDs 12 corresponding to control signal from the first printed circuit board 24.
The LED substrate 14 mounted with LEDs 12 is fixed to the mold frame 16, and the liquid crystal display panel 4, a light guide plate 18, a reflective plate 20 and optical sheets 10 are fixed to and supported by a step unit formed in the inner side surface of the mold frame 16. The bottom chassis 22 is fixed to the mold frame 16 in the lower side and outer side surface thereof as shown in FIG. 2 and an opening is formed in the part of the bottom chassis 22 such that a light emitting display panel 30 can be inserted therein.
The second printed circuit board 26 is supplied with the drive signal from a drive circuit (not shown) located in the mobile phone side and includes a mobile phone connector 28. The mobile phone connector 28 is combined with and fixed to another connector attached to the drive circuit located in the mobile phone side to be supplied with the drive signal from the drive circuit located in the mobile phone side. The second printed circuit board 26 supplied with the drive signal generates various control signals corresponding to the drive signal.
The first printed circuit board 24 is connected to the second printed circuit board 26 through a first pad unit 38 provided in the second printed circuit board 26. Additionally, the first printed circuit board 24 is connected to the integrated circuit 6 of the first liquid crystal display panel 4 and LED substrate 14 by a flexible printed circuit board (not shown). The first printed circuit board 24 connected to the integrated circuit 6 and LED substrate 14 drives the integrated circuit 6 and LED substrate 14 corresponding to the control signals supplied from the second printed circuit substrate 26.
The light emitting display panel 30 includes a first substrate 30a and a second substrate 30b. Organic LEDs (not shown) are arranged on the first substrate 30a in matrix form. The organic LEDs generate a predetermined amount of light corresponding to the amount of current supplied. The light emitting display panel 30 is connected to the second printed circuit board 26 by the second pad unit 36 of the flexible printed circuit board 32. An integrated circuit 34 is mounted on the flexible printed circuit board 32. The integrated circuit 34 lets the light emitting display panel 30 display a predetermined image in response to the control signals supplied from the second printed circuit board 26.
The portable display device may be exposed to various environments, making the display device susceptible to being impacted from the outside. Due to the recent trend of smaller and slimmer portable display devices, portable display devices are more likely to be damaged by impact. Thus, there is a need for a stiffer portable display device.